Many attempts have been made to provide a pole mounted device whereby fluorescent tubes can be installed and removed from lighting fixtures without the use of a step ladder by a person standing on a floor beneath a lighting fixture in conditions in which the lighting fixture is located several feet above that floor and out of arms reach of that person.
Fluorescent tubes commonly are provided with contact pins at their respective ends which must be properly positioned within spaced socket members carried by the lighting fixture. Thus the installation or removal of fluorescent tubes from lighting fixtures in such remote locations involves considerably more than providing a simple spring-loaded clamp at the end of a pole and which can be pushed upwardly to engage the fluorescent tube, to permit its installation or removal.
This must be accomplished in one of two ways, the first being in respect of fluorescent tubes provided with dual contact pins at their respective ends. Tubes of this type must be rotated through 90 degrees in order to properly position the contact pins within the respective socket members, or, in order to remove the pins and thus the fluorescent tube from the respective socket members.
The second way is in respect of fluorescent tubes provided with but a single contact pin at each of its ends. Tubes of this type must be moved axially of their longitudinal axis against spring-loaded contacts of the respective socket members in order to install or remove the fluorescent tube. Additionally, it is highly desirable that fluorescent tubes of this type be rotated, prior to removal and subsequent to installation, as there is a tendency of the pins to stick within the sockets due to the build-up of dust, dirt or other debris in the sockets.
Quick, U.S. Pat. No. 2,394,988 and Panzica, U.S. Pat. No. 2,819,922 teach devices for rotating a fluorescent tube of the first type about its longitudinal axis to permit installation or removal of such fluorescent tubes from a lighting fixture. Both Quick and Panzica teach a pole mounted device in which a spring loaded cradle is supported on the end of a pole in a manner permitting swinging movement of the cradle through an angle of 90 degrees from a position in which is extends transverse to the longitudinal axis of the pole, to a position in which it extends laterally of the pole axis.
However, such devices only can be employed in situations where there is sufficient free space laterally within the fixture or between adjacent fluorescent tubes in a multiple tube arrangement of fixture in order to accomodate the required lateral swinging movement of the cradle. This precludes the use of the device in tight spaces, and where a multiple array of fluorescent tubes is provided in closely spaced adjacent relationship within the lighting fixture.
This problem is eliminated by Switzer, U.S. Pat. No. 2,381,563 and Van Gerven, U.S. Pat. No. 3,776,584, both of which teach a device by which a fluorescent tube can be held and rotated about its longitudinal axis through 90 degrees without requiring movement of the cradle in directions laterally of the pole.
Switzer accomplishes this by providing a cradle having spring loaded arms that is fixedly held on the pole end against movement relative thereto, and by providing a friction roller engagable with the fluorescent tube, the friction roller being rotatable by means of a lever and ratchet arrangement which is actuated by a pull cord.
The operation of the Switzer device thus requires the use of two hands, one being required to hold the pole and steady it against movement, and the other being required to actuate the ratchet mechanism by pulling on the pull cord.
Van Gerven teaches a device which includes a spring-loaded cradle having friction belts for holding and rotating a fluorescent tube. The belts are driven to rotate the fluorescent tube through 90 degrees about its longitudinal axis by rotating a separate drive shaft arranged co-axially within the pole, a right-angled drive gearing being provided for this purpose.
Van Gerven is thus encumbered with the same problem as is Switzer, in that two hands are required for the manipulation of the device, one for holding the pole steady and the other for rotating the drive shaft contained within the pole.